Bi-cruciate substituting total knee arthroplasty provides varus–valgus stability throughout the midflexion range

Abstract

BackgroundProper soft tissue balance is crucial for a successful clinical outcome after total knee arthroplasty (TKA). Bi-cruciate substituting (BCS)-TKA has been developed to more closely approximate normal knee characteristics. The purpose of the present study was to evaluate midflexion laxity before and after BCS-TKA using a navigation system, and assess the correlation between intraoperative laxity and the maximum flexion angle after surgery. MethodsFifty-one knees in 46 patients with osteoarthritis replaced with BCS prosthesis were assessed. Manual mild passive internal–external rotational and varus–valgus stress was applied to the knees, and the maximum total laxity was measured automatically by a navigation system before and after TKA. The correlations with the range of motion (ROM) were evaluated using Spearman's correlation coefficients (ρ). ResultsInternal–external stress assessment revealed no statistically significant difference at each flexion angle before and after BCS-TKA. In contrast, the varus–valgus stress assessment revealed that BCS-TKA had significantly decreased varus–valgus laxity from preoperative levels at 20–120° flexion angles. Furthermore, the maximum flexion angle at six months after surgery significantly correlated with the intraoperative laxity at deep flexion range. ConclusionBCS-TKA stabilized varus–valgus laxity to better than preoperative levels at midflexion range.